1. Field of Invention
This invention relates to linear drive systems and covers for elongated openings.
2. Description of Prior Art
One purpose of this present invention is to provide a simple and effective means to create linear motion. Frequently, linear drive systems are utilized in machines such as, but not limited to, gantry robots, automated welding machines, automated milling machines, and automated painting machines. Often, lead screws with lead nuts are utilized to move loads in these machines. In such implementations, the load is structurally connected to the lead nut and the load is moved by rotating the lead screw.
These implementations have several disadvantages. First, lead screws often have substantial mass and width and much power is required to move the load because of the inertia of the lead screw. Second, such an implementation often suffers from lead screw whipping. Third, multiple loads utilizing the same lead screw, where linear motion is generated only by rotation of the lead screw, cannot move independently. The present invention avoids these problems by rotating the lead nut, rather than the lead screw.
The purpose of this present invention is to provide a low-cost cover for an opening, yet allow access to the opening by a device or structure which travels along said opening.
Machines which include devices which travel along openings, where the devices and/or openings should be covered to prevent exposure to dust, etc., often utilize bellows or telescoping covers. These types of covers have the distinct disadvantage of taking space at the ends of the openings when in a compact position. Therefore, the structural member or members creating the opening must be longer than otherwise required in order to provide room for the cover. These types of covers are also expensive to employ, and the present invention provides a low cost solution to the problem.
Applicants have located prior art in the form of United States patents which may interest the examiner, although applicants believe that none of the prior art located anticipates nor renders obvious the present invention. The present invention utilizes a substantially stationary band as a cover, which is lifted from an opening by a bridge structure to allow access to the opening. None of the United States patents located by applicants utilize such a stationary band. The United States patents located by applicants are as follows:
a. U.S. Pat. No. 4,403,534, to Altendorf et al., on a movable protective hood for power tool of a work tool machine;
b. U.S. Pat. No. 4,543,021, to Adler, on a safety shield for a milling machine, drill press, and the like;
c. U.S. Pat. No. 4,813,462, to Linn, on an apparatus for confining and removing dust and other debris from a work region of a machine;
d. U.S. Pat. No. 4,802,392, to Striebig, on a method of extracting the wood dust collecting in vertical panel saws;
e. U.S. Pat. No. 4,613,261, to Maier et al., on a router tool;
f. U.S. Pat. No. 4,051,880, to Hestily, on dustless routers;
g. U.S. Pat. No. 3,824,890, to Zettler et al., on a chip guard for machine tools;
h. U.S. Pat. No. 3,366,012, to Richter, on a machine tool guard structure; and
i. U.S. Pat. No. 3,022,806, to Johnston, on a router dust guard.